Free Grade 3 Introducing Vertically Opposite Angles Essentials Lessons
Free Grade 3 lessons for Introducing Vertically Opposite Angles Essentials: 12 real questions with a full answer key and worked solutions. Angles on a straight line add to 180°, around a point to 360°, and inside a triangle to 180°. A polygon with n sides has interior angles adding to (n − 2) × 180°.
Free
Foundation
35 min
24
Learning objectives
Every objective is checkable, and each one maps to an activity and an assessment.
- RememberIdentify introducing vertically opposite angles essentials
Identify introducing vertically opposite angles essentials accurately in a familiar context.
Assessed by: Exit ticket of four short items
- UnderstandExplain introducing vertically opposite angles essentials
Explain introducing vertically opposite angles essentials accurately in a familiar context.
Assessed by: Exit ticket of four short items
- ApplyCalculate introducing vertically opposite angles essentials
Calculate introducing vertically opposite angles essentials accurately in a familiar context.
Assessed by: Exit ticket of four short items
- AnalyseCompare introducing vertically opposite angles essentials
Compare introducing vertically opposite angles essentials accurately in a familiar context.
Assessed by: Exit ticket of four short items
Prerequisites
Close these gaps first — each has its own free lesson, worksheet and quiz.
How Introducing Vertically Opposite Angles Essentials works
Angles on a straight line add to 180°, around a point to 360°, and inside a triangle to 180°. A polygon with n sides has interior angles adding to (n − 2) × 180°.
12 practice questions
Easy to hard, 24 marks in total. Try them first, then open the answers.
- 1.Two angles on a straight line. One is 50°. Find the other.[1]
- 2.Two angles on a straight line. One is 37°. Find the other.[1]
- 3.Two angles on a straight line. One is 65°. Find the other.[1]
- 4.Two angles on a straight line. One is 24°. Find the other.[1]
- 5.A triangle has angles 32° and 110°. Find the third angle.[2]
- 6.A triangle has angles 84° and 34°. Find the third angle.[2]
- 7.A triangle has angles 55° and 73°. Find the third angle.[2]
- 8.A triangle has angles 25° and 71°. Find the third angle.[2]
- 9.Find the size of each interior angle of a regular 10-sided polygon.[3]
- 10.Find the size of each interior angle of a regular 7-sided polygon.[3]
- 11.Find the size of each interior angle of a regular 9-sided polygon.[3]
- 12.Find the size of each interior angle of a regular 6-sided polygon.[3]
Show answers and working
1. 130°
Angles on a straight line add to 180°. 180 − 50 = 130°.
2. 143°
Angles on a straight line add to 180°. 180 − 37 = 143°.
3. 115°
Angles on a straight line add to 180°. 180 − 65 = 115°.
4. 156°
Angles on a straight line add to 180°. 180 − 24 = 156°.
5. 38°
Angles in a triangle add to 180°. 180 − 32 − 110 = 38°.
6. 62°
Angles in a triangle add to 180°. 180 − 84 − 34 = 62°.
7. 52°
Angles in a triangle add to 180°. 180 − 55 − 73 = 52°.
8. 84°
Angles in a triangle add to 180°. 180 − 25 − 71 = 84°.
9. 144°
Sum of interior angles = (10 − 2) × 180 = 1440°. Each angle = 1440 ÷ 10 = 144°.
10. 128.57°
Sum of interior angles = (7 − 2) × 180 = 900°. Each angle = 900 ÷ 7 = 128.57°.
11. 140°
Sum of interior angles = (9 − 2) × 180 = 1260°. Each angle = 1260 ÷ 9 = 140°.
12. 120°
Sum of interior angles = (6 − 2) × 180 = 720°. Each angle = 720 ÷ 6 = 120°.
Worked examples
Two angles on a straight line. One is 36°. Find the other.
- Angles on a straight line add to 180°.
- 180 − 36 = 144°.
- Answer: 144°
A triangle has angles 41° and 113°. Find the third angle.
- Angles in a triangle add to 180°.
- 180 − 41 − 113 = 26°.
- Answer: 26°
Find the size of each interior angle of a regular 8-sided polygon.
- Sum of interior angles = (8 − 2) × 180 = 1080°.
- Each angle = 1080 ÷ 8 = 135°.
- Answer: 135°
Interactive practice
Free, no account required — answer on screen or print it.
Common mistakes
What learners typically get wrong, and how to fix it.
Reads the wrong scale on a protractor.
Correction: Start from the 0 on the arm you are measuring from.
Uses 360° for a triangle.
Correction: Triangle = 180°, quadrilateral = 360°.
Teacher tips
- · Estimate the angle type before measuring.
Parent tips
- · Spot right angles around the house.
Real-life applications
- · Ramps, clock hands, building and design.
Assessment objectives
How mastery is evidenced, and which standards it maps to.
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Frequently asked
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- Yes. Every lessons on FreeMathWorksheet is free to use, print and share — no account, no paywall and no watermark.
- What should a learner already know before this?
- Start with Angles Around a Point. Each one has its own free lesson, worksheet and quiz.
- How is the lesson sequenced?
- Recognition first, then understanding, application, reasoning and finally mastery — the same ladder used across every free resource on the platform.
- What comes next after Introducing Vertically Opposite Angles Essentials?
- Move on to Introducing Vertically Opposite Angles Techniques, Introducing Vertically Opposite Angles Word Problems, Introducing Vertically Opposite Angles Common Errors, Working with Vertically Opposite Angles, which build directly on this idea.
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